This invention relates to a heat exchanger with a novel seal means for at least one tube sheet of the tube bundle in said heat exchanger. The seal means construction for the tube sheet of the heat exchanger, permits one to easily disassemble the heat exchanger and easily remove the tube bundle with the tube sheets as a singly unit to facilitate cleaning both the exterior and interior of the tube bundle as well as the shell interior surfaces.
There are various types of heat exchangers used in a horizontal or vertical position for different processes known in the art. For example, in a process for heating a liquid circulating in a distillation column, a reboiler type heat exchanger is used.
Conventional reboilers are usually horizontal, kettle-type reboilers employing a removable "U" type tube bundle. This configuration of reboiler has the disadvantage of being unstable in maintaining a constant liquid head. A constant liquid head is essential to efficient circulation and heat transfer. Another disadvantage of the "U" type tube bundle, horizontal reboiler is that a "U" tube bundle is difficult to clean, especially if the bundle is in fouling service.
A vertical type thermosyphon exchanger is more economical, efficient, and easily operative and maintained when needed to reboil, for example, the bottoms liquid on a conventional fractionating column.
Vertical thermosyphon reboilers are generally fixed tube type reboilers. The fixed tube characteristic of the reboiler precludes the reboiler's use in sensible heat transfer when the heating (shell side) medium is of a fouling nature requiring removal of the tube bundle for cleaning.
A vertical reboiler containing a conventional floating head bundle in the vertical position cannot effectively seal the shell side materials from the tube side materials and cross contamination of the two streams is inevitable. The use of a conventional lantern ring type of exchanger is limited by the materials of construction of the lantern ring and the effectiveness of the seal ring.
Since the tube bundle must not only be cleaned on the tube side by the usual means such as "hydroblasting", it must also be able to be removed from its shell without causing bundle distortion so that the shell side can be cleaned. Distortion affects the flatness of the flanged mating surfaces of the shell, bundle and heads.
It is desired to circumvent the problems of the prior art reboilers by providing a heat exchanger, preferably of the vertical type with a novel seal means for at least one of the tube sheets which prevents leakage between the shell and tube side contents. It is also desired to provide a heat exchanger that can be easily disassembled for cleaning and repair.